Magnesium sulfate is a medication that has been in widespread use in the management of two common complications of pregnancy: 1) Preeclampsia - a high blood pressure problem of pregnancy and 2) Pemature labor - labor which occurs early, befoe the baby is full term. Although widely used, there is little known about the pharmacokinetics of the drug for premature labor. There is also little comparison of the drug's effect in preeclampsia and premature labor. This study seeks to systematically study the pahrmacokinetics of magnesium in preeclampsia, premature labor as well as describe the free magnesium levels alongside the standard total magnesium levels.